| HS Code | 119231 |
| Oxygen Barrier | Very low oxygen transmission rate |
| Nitrogen Barrier | Excellent barrier to nitrogen gas |
| Carbon Dioxide Barrier | Excellent barrier to carbon dioxide gas |
| Aroma Barrier | Prevents aroma and flavor loss or transfer |
| Transparency | High optical clarity |
| Gloss | High surface gloss |
| Oil Resistance | Resists oils, fats, and greases |
| Chemical Resistance | Resists organic solvents |
| Printability | Compatible with printing processes |
| Lamination Adhesion | Admits strong adhesion to laminating layers |
| Mechanical Strength | Good tensile strength |
| Heat Resistance | Suitable for heat processing |
As an accredited KURARISTER Transparent High-Barrier Film factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | KURARISTER Transparent High-Barrier Film is supplied in one roll per sealed bag, protected from moisture and physical damage. |
| Container Loading (20′ FCL) | 20′ FCL container loading: KURARISTER Transparent High-Barrier Film, securely packed in rolls/pallets, maximizing space with moisture-protective packaging. |
| Shipping | Ship in moisture-proof, shock-resistant packaging to preserve barrier properties. Avoid direct sunlight, high heat, and humidity during transit. Store flat or rolled on sturdy cores, with no sharp objects. Ensure sealed, labeled handling to prevent scratches, deformation, or contamination. |
| Storage | Store KURARISTER Transparent High-Barrier Film in its original packaging in a cool, dry, clean area. Avoid direct sunlight, high humidity, and temperature extremes to prevent degradation. Keep films flat or vertically upright to prevent creasing, and handle carefully to avoid scratches. Ensure the storage area is well-ventilated and free from dust, chemicals, or sharp objects. |
| Shelf Life | Shelf life is typically 12 months when stored in original packaging under cool, dry conditions. |
In retort pouch converting, KURARISTER Transparent High-Barrier Film is used as a foil-replacement barrier web where metal-free construction, microwave reheating and optical clarity are required. The typical lamination runs on a 1,200 mm solventless laminator with a two-component polyurethane adhesive applied at 2.0–3.5 g/m², followed by nipping at 70–80 °C and curing at 40 °C for 72 h or 50 °C for 24 h with a fast-cure system. In a 15 µm KURARISTER / 60 µm cast polypropylene structure, the barrier layer represents 20 % of total thickness; when a 12 µm oriented polyester print web is added and the sealant is reduced to 50 µm LLDPE, total thickness reaches 77 µm and the barrier layer ratio becomes 19.5 %. Downstream pouch making uses heat-seal jaws at 160–190 °C, pressure 0.3–0.6 MPa and dwell 0.8–1.5 s. Retort processing at 121 °C for 30 min or 135 °C for 10 min requires overpressure of 0.18–0.20 MPa to prevent seal creep and delamination. Failure modes observed on production lines include barrier-layer stress cracking at gusset folds, seal contamination by oil-containing food products and retort-shock delamination when curing is incomplete. Food-contact compliance is verified under EU Regulation 10/2011 with overall migration below 10 mg/dm², and US components are referenced to FDA 21 CFR 177.1390 for laminate clearance. Oxygen transmission after retort is measured per ASTM D3985 at 23 °C and 0 % RH, while seal strength is checked per ASTM F88. Terminal product types include ready-to-eat rice pouches, curry pouches, retorted baby food, pet food pouches and high-water-activity soup pouches.
The substitution of foil lidding with a transparent barrier web in strip-pack lines requires control of seal initiation temperature, post-seal cooling and web flatness because asymmetric shrinkage can curl the finished unit dose. A reciprocating strip-pack machine operating at 40–120 cycles/min seals two webs between servo-driven jaws at 140–170 °C, dwell 0.4–0.8 s and pressure 0.3–0.5 MPa. The lamination structure is typically 20–25 µm KURARISTER / 30–40 µm LDPE sealant, giving a total thickness of 50–65 µm and a barrier layer ratio of 33–40 % by thickness. For moisture-sensitive actives, a secondary cold-seal or peel layer is not used unless the product requires child-resistant opening, because additional coatings can shift the seal window by 5–10 °C. Compliance for pharmaceutical primary packaging is anchored to USP <671> for moisture vapour permeation, Ph. Eur. 3.2.2 for plastic containers and closures, ISO 15378:2017 for GMP-relevant packaging materials and FDA 21 CFR 177.1390 where the laminate is also used for food-contact presentations. Seal integrity is evaluated per ASTM F88 after conditioning at 40 °C and 75 % RH for 14 days to detect adhesive cure drift. Terminal product types include unit-dose oral powders, effervescent tablets, granule sachets, diagnostic test strips and desiccant-containing packages.
| Standard / Test method | Parameter | Verification condition |
|---|---|---|
| USP <671> | Water vapour permeation | 38 °C, 90 % RH |
| Ph. Eur. 3.2.2 | Plastic container suitability | Pharmacopoeial test battery |
| ISO 15378:2017 | GMP primary packaging | Batch traceability and hygiene |
| FDA 21 CFR 177.1390 | Laminate food-contact clearance | Migration testing under end-use conditions |
After desiccant loading and vacuum draw-down, the top web in semiconductor packaging must maintain water vapour transmission below the point at which internal desiccant reaches 6 % weight gain before the rated shelf life. A standard moisture-barrier structure pairs 25 µm KURARISTER with 60 µm LLDPE, giving total thickness of 85 µm and a barrier layer ratio of 29.4 %. When component leads create puncture risk, a 12 µm oriented polyester outer layer is adhesive-laminated to the barrier web, lifting total thickness to 97 µm and reducing the KURARISTER share to 25.8 %. Lamination occurs on a 1,300 mm solventless line at 300 m/min, followed by slitting to 250–450 mm roll widths. Vacuum sealing in a Class 5 cleanroom uses impulse seal bars at 120–160 °C, final chamber vacuum below 10 mbar and nitrogen backfill with dew point below -30 °C. Compliance is verified against MIL-PRF-81705D, ANSI/ESD S541-2019, IEC 61340-5-1 and ASTM F1249-20 at 37.8 °C and 90 % RH. Terminal product types include wafer cassettes, MEMS sensors, optoelectronic components, printed circuit boards and precision connectors.
Tray lidding lines for high-respiring produce operate at 12–18 cycles/min and use a thin barrier web to restrict oxygen ingress while a sealant layer provides antifog performance and peelable opening. The top web is constructed from 12 µm KURARISTER and 35 µm EVA sealant, total 47 µm, with the barrier layer representing 25.5 % of total thickness. Sealing to PET or PP trays occurs at 150–190 °C, pressure 0.4–0.7 MPa and dwell 0.6–1.0 s; gas flushing maintains oxygen concentration between 3 % and 8 % depending on respiration rate. Peel initiation is typically controlled to 8–15 N/15 mm to prevent consumer opening difficulty while retaining seal integrity during distribution. Compliance references EU 10/2011 for food contact, FDA 21 CFR 177.1345 for EVA sealant clearance, ASTM D3985 for oxygen transmission and ASTM F88 for seal strength. Terminal product types include fresh-cut salad, baby leaf spinach, berries, cherry tomatoes and ready-to-eat fruit mixes.
Because volatile aroma compounds such as limonene and linalool diffuse rapidly through polyethylene, high-fragrance cosmetic formulations require a barrier layer that lowers aroma loss without introducing foil flex-crack noise. A typical refill pouch structure combines 12 µm printed PET, 15 µm KURARISTER and 50 µm LLDPE, yielding total thickness of 77 µm and a barrier layer ratio of 19.5 %. The PET outer web is printed on an 8–10-station rotogravure press at 250–350 m/min, then adhesive-laminated to KURARISTER and extrusion-laminated to LLDPE. Pouch making uses heat-seal jaws at 160–200 °C with pressure 0.4–0.6 MPa; filling lines run at 25–40 pouches/min. Aroma retention is assessed by gas chromatography headspace analysis after accelerated storage at 40 °C for 28 days, while overall packaging safety is governed by EU 1223/2009 for cosmetic products, EC 1935/2004, EU 10/2011 and REACH. Published data for KURARISTER under sustained high-ester fragrance load is limited, so converter qualification includes laminate migration testing and seal-strength retention. Terminal product types include shampoo refill pouches, hair mask sachets, serum sachets and sunscreen pouches.
On vertical form-fill-seal lines running moisture-curing polyurethane sealants, transparent barrier film permits visual fill-level inspection while preventing ambient moisture from causing premature skin-over in the package. The structure is 20 µm KURARISTER / 60 µm LLDPE, total 80 µm, with the barrier layer at 25 % of total thickness. Filling volumes range from 0.5 kg to 5 kg, with seal jaws at 150–190 °C and pressure 0.5 MPa; cooling jaws after sealing reduce post-seal creep that can occur with soft LLDPE sealant layers. Transport compliance is confirmed under REACH and the applicable ADR/RID/IMDG limited-quantity provisions. Because published barrier data for continuous contact with polar plasticizers from polyurethane systems remains limited, qualification at 40 °C and 90 % RH is required before production release. Terminal product types include 300–600 mL sealant sausage packs, 1–5 kg moisture-curing adhesive packs and industrial mastic cartridges.
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KURARISTER Transparent High-Barrier Film is a rollstock barrier material supplied by Kuraray Co., Ltd. for lamination into flexible packaging structures where oxygen ingress control, optical clarity, and retort resistance are specified. The film combines a biaxially oriented polyester carrier with a cross-linked organic–inorganic barrier layer. Unlike aluminum foil, the material remains transparent and is compatible with microwaveable packaging concepts. Unlike conventional EVOH, the barrier mechanism is designed to reduce the severity of humidity-dependent oxygen transmission loss in high-moisture and retort environments. Current commercial grade availability includes multiple carrier thicknesses and barrier-layer variants. Converters should confirm exact grade code, roll width, core type, and lot-specific barrier data against the current Kuraray technical datasheet before specifying the material for production.
On a three-layer dry-bond laminating line running at 120 m/min, web tension between the unwind and laminating nip is typically set at 15–25 N/m for polyester-based transparent barrier rollstock. Tension above 30 N/m produces blocking wrinkles when the barrier layer faces the heated combining roll. The film is corona treated in-line to a target surface energy of 38–42 mN/m before adhesive application. A two-component solventless polyurethane adhesive applied at 2.0–3.5 g/m² with a roller temperature of 40–50 °C provides initial bond. Curing at 40 °C for 48 h is used to develop chemical resistance before retort testing. Production-scale variation in coating adhesion has been observed when relative humidity during lamination exceeds 60 %; pre-conditioning of the rollstock at 23 ± 2 °C and 50 % RH for 24 h is therefore recommended.
The barrier film is constructed on a transparent polyester base, available in common carrier thicknesses of 12 µm, 16 µm, and 25 µm. The functional barrier layer is deposited as a sub-micron coating. Grade selection in commercial converting is driven by three variables: carrier thickness, barrier-layer formulation generation, and the intended lamination position. Thinner carriers are specified for low-weight pouch structures where flex crack resistance and downstream sealing throughput are dominant. Thicker carriers are selected for retort lids and thermoformable constructions requiring greater dimensional stability. Published data for the exact alphanumeric grade code structure is limited to the current Kuraray technical datasheet, but the commercial range is differentiated by coating formulation rather than by a single universal barrier chemistry.
Oxygen transmission is grade-dependent. Values obtained using a MOCON OX-TRAN 2/22 under ASTM D3985 at 23 °C and 0 % RH are generally below 1 cm³/(m²·day·atm) for the high-barrier grades. At 90 % RH, oxygen transmission increases by a factor that depends on barrier-layer hygroscopicity, coating adhesion, and carrier thickness. Water vapour transmission measured under ASTM F1249 at 38 °C and 90 % RH is influenced more strongly by the polyester carrier and subsequent lamination layers than by the oxygen-barrier coating alone. For this reason, the film is not specified as a moisture-barrier monofilm; it is specified as the oxygen-control layer within a complete laminate.
Tensile properties are measured according to ISO 527-3 at 23 °C and 50 % RH. Typical polyester-based carrier films of this class exhibit machine-direction tensile strength in the range of 200–260 MPa and elongation at break of 90–140 %. Optical clarity is assessed through total luminous transmittance and haze using ASTM D1003. Transparent high-barrier films intended for retort applications are also tested for coating adhesion by cross-hatch tape pull according to ASTM D3359, because adhesion loss after retort is a principal cause of barrier failure in laminated pouches.
Retort processing exposes flexible packaging laminates to temperatures of 121 °C for 30 min or, in higher-severity protocols, 135 °C for 10 min. Under these conditions, inorganic barrier layers such as silicon oxide or aluminum oxide on polyester can develop microcracks because the inorganic layer cannot follow the thermal expansion and contraction of the polyester carrier. The resulting barrier loss is partially irreversible. The KURARISTER material is designed around a cross-linked organic–inorganic barrier layer that retains adhesion and reduces the formation of retort-induced microcracks. Packaging engineers should nonetheless quantify barrier retention after retort because the lamination adhesive, sealant layer, and filling headspace gases also affect final oxygen ingress.
Flex-crack resistance is evaluated with a Gelbo flex tester in accordance with ASTM F392, commonly at 440° twist and 25 cycles. The barrier retention after flexing is compared with the unflexed control sample. Transparent inorganic-coated films often show measurable barrier loss after repeated flexing, particularly when the barrier layer is placed on the outer-facing side of the laminate. The KURARISTER barrier architecture is positioned to reduce the magnitude of barrier loss in high-flex applications such as stand-up pouches, retort pouches, and liquid refill packs. Nevertheless, published data for all commercial grades under all flex and retort combinations is limited; lot-specific validation is required before qualifying any packaging structure for long-term shelf-life claims.
Gas barrier after retort is also affected by oxygen permeability through the sealant edge and around zipper profiles. In practice, a pouch made with a high-barrier transparent film can still exhibit elevated oxygen ingress if the sealant layer has poor oxygen barrier and the seal area is large. Therefore, the oxygen barrier contribution of the KURARISTER layer should be quantified on the finished pouch using a headspace gas analyser or oxygen ingress rate calculation, not on the film alone. The film specification is only one layer in a system that includes print web, adhesive, barrier layer, sealant, and closure geometry.
The KURARISTER film is not a sealant layer. It is positioned between an outer print web and a sealant film such as retort-grade cast polypropylene, polyethylene, or a coextruded sealant structure. In retort pouch construction, the sealant is often a 60–80 µm cast polypropylene film sealed at 180–220 °C with a sealing pressure of 0.3 MPa and dwell time of 1.0–2.0 s. If the sealant layer is too thin or the sealing temperature is below the melting range of the sealant resin, channel leaks can develop along the seal edge, independent of the barrier film performance. Production lines that switch from aluminum-foil-based laminates to transparent barrier laminates commonly require adjustment of sealing jaw temperature because the transparent laminate heats faster and can show seal-edge deformation at the same machine settings.
Lamination adhesives for high-barrier transparent films must be selected for retort resistance and chemical resistance to acidic or oily fillings. A two-component polyurethane adhesive designed for retort contact is generally cured at 40 °C for 48 h or at ambient temperature for 7 days before retort testing. In complete laminates, barrier performance is influenced by adhesive coverage uniformity. Gravure or smooth-roll application should maintain a dry coat weight between 2.5 g/m² and 3.5 g/m². Lower coat weights can create adhesive-starved areas at the edges of printed areas; higher coat weights can increase solvent retention and produce tunnel formation after retort. The barrier layer should face the adhesive in a way that avoids direct contact with the sealing jaw, because the barrier layer is not designed to withstand direct heat-seal contact.
On high-speed vertical form-fill-seal equipment operating at 80 packages/min, film-to-metal friction and heat transfer through the laminate affect the temperature at the sealing interface. Transparent high-barrier rollstock tends to exhibit lower heat-insulating behaviour than aluminum-foil-based laminates, which can reduce the seal bar setpoint needed to reach the same interface temperature. Processing parameters should be re-qualified when moving from foil-based to transparent barrier film. In-mould labelling and thermoforming operations using KURARISTER as a heat-resistant lidding layer require additional attention to forming temperature and coating orientation; published data for this specific configuration is limited, and pilot-line testing is recommended.
The principal transparent high-barrier film technologies differ in humidity dependence, retort resistance, flex-crack resistance, and regulatory profile. EVOH provides excellent oxygen barrier at low humidity but loses oxygen barrier at relative humidity levels above approximately 60–70 % RH, depending on ethylene content. EVOH is therefore used as an internal layer surrounded by moisture-protective polyolefin layers. PVDC-coated polyester provides humidity-independent oxygen barrier but the chlorine content introduces waste-incineration and recycling considerations. Silicon oxide or aluminum oxide-coated polyester offers transparency and oxygen barrier but is susceptible to microcrack-induced barrier loss after flexing and retort. Aluminum foil provides near-zero oxygen transmission but is opaque, cannot be used in microwaveable packaging, and develops flex cracks that lead to pinholes.
| Technology | Transparency | High-humidity oxygen barrier behaviour | Retort resistance | Flex-crack resistance | Principal limitation |
| KURARISTER transparent high-barrier film | Transparent | Grade-dependent; designed for barrier retention under high RH and after retort | High, but laminate must be qualified | High relative to inorganic-coated PET | Requires lamination to sealant; no direct heat-seal surface |
| EVOH | Transparent | Oxygen barrier declines above 60–70 % RH | Moderate; requires protective layers | Moderate | Humidity sensitivity requires buried placement |
| PVDC-coated PET | Transparent | Humidity-independent oxygen barrier | Moderate | Moderate | Chlorine content and thermal decomposition issues |
| SiOx or AlOx-coated PET | Transparent | Good oxygen barrier, but microcracking increases transmission | Moderate | Low to moderate | Barrier loss after flexing and retort |
| Aluminum foil | Opaque | Near-zero gas transmission | Excellent, but flex cracks reduce gas barrier | Poor flex-crack resistance | Opacifies package and cannot be used in microwave applications |
The table above is a comparative technology matrix derived from commonly reported converting industry data. It does not replace grade-specific datasheet values. For KURARISTER grades, the exact oxygen transmission after retort is dependent on the carrier thickness, lamination structure, adhesive coverage, sealant layer, and retort severity. Published data for this specific configuration is limited in public literature; therefore, qualifying tests should be performed on the final laminate rather than on the film in isolation.
Regulatory compliance for food-contact use must be verified under the intended food simulants and time–temperature conditions. Polyester-based films are generally evaluated under Regulation (EU) No 10/2011 or FDA 21 CFR sections applicable to the substrate and coating assembly. Compliance with REACH and RoHS may also be required for non-food technical packaging. The barrier coating is not a sealant and should not be placed in direct food contact unless the specific grade is expressly listed for that purpose in the current technical datasheet. Operation outside the manufacturer’s stated lamination and processing conditions can invalidate barrier-performance claims.
When migrating from aluminum foil to transparent high-barrier rollstock, the filling line setpoints for sealing temperature, sealing pressure, and cooling time must be re-established. A transparent laminate transfers heat differently through the sealing jaw, and the visual appearance of the seal area is not equivalent to foil-based sealing. Seal inspection systems using optical or ultrasonic methods may require bespoke calibration when the laminated layer stack no longer contains metal. Production-scale observation shows that seal-area deformation and channel leaks can occur when the sealant thickness is below 50 µm in retort pouch formats, independent of the barrier film. These operational boundaries define the practical limit of the material: it provides oxygen barrier and clarity, but it does not provide sealing, rigidity, or abuse resistance by itself.
